1. Field of the Invention:
The field of art to which this invention pertains includes shift control systems for multiple input - multiple output transmissions which provide a plurality of speed ratios in response to the movement of an operator's shift lever or the like.
2. Description of the Prior Art:
A manual shift control system is jointly disclosed in U.S. Pat. Nos. 4,155,271, 4,170,148 and 4,197,760, all assigned to the Assignee of the present invention, utilizing input and output control shafts inserted through cutouts in respective input and output shift rails. The control shafts are rotatable in response to shift lever movement.
The control system in the above-cited prior art has an expanded "H" shift pattern to provide for nine forward speed ratios and one reverse speed ratio. One disadvantage to this type of control system is that it is difficult for the operator of the shift lever to always be aware of his position in the shift pattern.
The prior art also includes movable shift forks selectively engageable with the lower end of a shift lever. A plunger assembly is operably associated with the shift fork for resisting movement of the shift fork past a predetermined distance in a selected direction. Although in a five speed forward transmission the plunger assembly performs satisfactorily, it is believed that as the number of speed ratios increase, additional plunger assemblies necessary to provide variable resistance would make the transmission unduly complicated, cumbersome, inefficient and expensive to manufacture. Moreover, the engagement between the lower end of shift lever and the shift fork may not be practical when additional speed ratios are added.